Certainly not commonplace, but I took the shower rods of Wenko as clamping bars for curtains in operation. They can be of great wall clamp to wall. Surely so many have already experienced to drill a hole in an old building wall a nasty surprise when you try. Suddenly it crumbles from the wall and you have to buy special plugs to tighten something around. That you can save with the clamping bar and it simplifies the attachment of loop scarves. One can also work with curtain rings and thus back every curtain in the right light. The window frame must not be pasted also, the rod can be as far forward and upward to pinch, that the window can tilt easily or completely open.
